Hybrid transmission for a vehicle

ABSTRACT

A hybrid transmission for a vehicle includes a transmission input shaft extending in a transverse direction, at least one countershaft arranged parallel to the transmission input shaft, a clutch device arranged coaxially with respect to the transmission input shaft and which has at least one clutch, and a differential having a differential input gear. A rotational axis of the differential input gear is arranged parallel to the transmission input shaft. The transmission also includes an electric machine having a rotor with a rotor rotational axis arranged parallel to the transmission input shaft and a transmission control device. As viewed in a longitudinal direction perpendicular to the transverse direction, the differential input gear, the transmission input shaft, and a transmission controller including the transmission control device are arranged in succession in the sequence specified.

BACKGROUND AND SUMMARY OF THE INVENTION

Exemplary embodiments of the invention relate to a hybrid transmissionfor a vehicle.

Hybrid transmissions for vehicles are known in principle from the priorart. In this respect, the substantial aim is always to achieve astructure of the transmission that is as efficient and compact aspossible. For example, DE 10 2010 002 746 A1 describes the integrationof an electric machine together with its power electronics system into ahybrid transmission. The structure is in this case such that theelectric machine is used in a so-called inline arrangement, i.e.,coaxial with the main gear shaft.

A dual clutch transmission for a motor vehicle is known from the furtherprior art in the form of DE 10 2018 002 167 B3. In this case, anelectrohydraulic control unit is arranged in the oil chamber in order tosave installation space. Since this electro-hydraulic system consists,on the one hand, of electronics, and on the other hand, of the hydraulictransmission controller, the transmission control device, whichgenerally is to be understood as the electronic controller of thetransmission, is thus also integrated into the structure of thetransmission, into the transmission housing in this case.

Furthermore, DE 11 2014 001 112 T5 discloses a hybrid transmission inwhich a hydraulic controller and an electric machine are arranged in oron a housing of the hybrid transmission.

Finally, a hybrid transmission is known from DE 11 2009 000 022 B4, inwhich power electronics of an electric machine and a transmission arearranged together in an integrated housing.

In spite of these documents, there is still a great optimizationpotential with regard to the most compact possible design of hybridtransmissions, in particular in their axial direction along the maingear shaft, in order to achieve the most compact possible design andhigh power density.

Accordingly, exemplary embodiments of the present invention are directedto a hybrid transmission for a vehicle that can be made even morecompact.

In a hybrid transmission for a vehicle, the known design as in the priorart initially comprises a transmission input shaft extending in atransverse direction and at least one countershaft arranged parallelthereto. In addition, a clutch device is provided, which can preferablybe designed as a dual clutch, as a disconnect clutch, or as acombination thereof. In particular, the structure in the embodiment as adual clutch comprises two countershafts; in the embodiment as a meredisconnect clutch, it comprises one countershaft. Furthermore, adifferential is provided that has a differential input gear, therotational axis of which is arranged parallel to the transmission inputshaft, that is to say the direction referred to in the structureaccording to the invention as the transverse direction. An electricmachine with a stator and a rotor is likewise arranged in such a mannerthat the rotor rotational axis runs parallel to the transmission inputshaft. A transmission control device, via which an electronictransmission control is achieved, is provided. As viewed in alongitudinal direction arranged perpendicularly to the aforementionedtransverse direction, the differential input gear, the transmissioninput shaft, and the transmission control device are arranged insuccession in the sequence specified.

The transmission control device is understood to mean an electroniccontrol device used to control actuator elements for shifting units of agear set of the hybrid transmission. In a manner known per se, theactuator elements can be hydraulic actuator elements orelectromechanical actuator elements, or a mixed form of both. In thecase of hydraulic actuator elements, the transmission control devicecontrols, for example, solenoid valves and a hydraulic pump. In the caseof electromechanical actuator elements, the transmission control devicecontrols servomotors, for example. Advantageously, the transmissioncontrol device is furthermore designed to control a lubricating andcooling system of the gear set in a manner known per se. Advantageously,the transmission control device can also be designed to control acooling system of the electric machine.

Furthermore, in a vertical direction arranged perpendicularly both tothe transverse direction and to the longitudinal direction, at least onepart of a power electronics system for the electric machine is arrangedin a manner known per se, and specifically, advantageously adjacently tothe transmission control device. This part of the power electronicssystem comprises the structurally largest part thereof but, in any case,a circuit board of an inverter. This arrangement provides anextraordinarily efficient and compact structure. High system integrationis possible in this way, enabling a correspondingly high power densityof the hybrid transmission according to the invention. In addition, sucha structure, which can be designed in a correspondingly compact manner,can be adapted to the installation space requirements in theconstruction of the vehicle in an ideal manner with regard to thepacking of components.

According to the invention, it is provided that the electric machine isarranged adjacently to and above a hydraulic transmission controller inthe vertical direction and overlapping it in the longitudinal direction.An installation space in which the gear set of the hybrid transmissionis arranged together with the transmission input shaft and the at leastone countershaft, the electric machine, the control device, and thehydraulic transmission controller can thus be utilized in an idealmanner, wherein the hydraulic transmission controller is preferablyarranged in the longitudinal direction adjacently to the control device.

The hydraulic transmission controller in this case comprises at leastcontrol valves, for example solenoid valves, which are used for shiftinggear actuators of the gear set. Advantageously, the hydraulictransmission controller also comprises valves which are used forcontrolling a lubricating and cooling system of the hybrid transmission.The hydraulic transmission controller is electrically connected to thetransmission control device.

The power electronics system is understood to mean an electronics unit,which is known per se and is assigned to the electric machine. The powerelectronics system is used to control the electric machine.

The gear set of the hybrid transmission is understood to mean a part ofthe hybrid transmission serving to form different transmission speeds,that is to say different gear ratios. The gear set comprises at leastthe input shaft, the countershafts, and gearwheels and shifting unitsarranged coaxially with these shafts in each case.

The compactly constructed hybrid transmission with a high power densityenables an optimized structure with regard to the crash requirements forvehicle body shell construction, which enables a further decisiveadvantage in such a vehicle having the hybrid transmission in the highadditional masses resulting in particular from the traction battery.

An arrangement of a rotatably mounted element parallel to a direction isunderstood to mean that a rotational axis of the rotatably mountedelement is arranged parallel to the direction. Accordingly, a parallelarrangement of two rotatably mounted elements is understood to mean thatthe rotational axes of the two elements are arranged in parallel. Acoaxial arrangement of two other, rotatably mounted elements isunderstood to mean that the two other elements have the same rotationalaxis. The clutch device being arranged coaxially with the transmissioninput shaft is understood to mean that rotatably mounted clutch disks orclutch plates are arranged coaxially with the transmission input shaft.

According to an extraordinarily favorable development of the hybridtransmission according to the invention, the at least one part of thepower electronics system is arranged in the vertical direction above thetransmission control device when used as intended. This structureenables further optimization. In this case, the transmission controldevice can be arranged in the transmission oil, the power electronicssystem then preferably being located above the transmission controldevice, preferably adjacently to the electric machine as viewed in thelongitudinal direction.

According to a further, very favorable embodiment of the hybridtransmission according to the invention, it can also be provided that apart of the power electronics system extends in the longitudinaldirection and is arranged above the electric machine in the verticaldirection. In this case, the power electronics system is thussubstantially L-shaped when viewing the structure in the transversedirection and is partially adjacent, preferably above, the transmissioncontrol device and partially above the electric machine so that thepower electronics system can partially surround the electric machine andthus be integrated even more efficiently into the existing installationspace.

According to an extremely favorable development of the hybridtransmission according to the invention, the power electronics systemcan be arranged at least partially overlapping the transmission controldevice in the longitudinal direction and/or the transverse direction.This saves further installation space in that, depending on thedimensions of the transmission control device on the one hand and thepower electronics system on the other hand, they are arrangedoverlapping in one or the other direction.

A further extraordinarily favorable embodiment furthermore provides thata circuit board of an inverter of the power electronics system isadjacent in the vertical direction and parallel in the longitudinaldirection to a circuit board of the transmission control device. Thisarrangement with adjacent circuit boards, which are spaced less than 20mm in the longitudinal direction in accordance with an exceptionallyfavorable development of this concept and are preferably even arrangedflush in the vertical direction, creates a very efficient use of theinstallation space in the longitudinal direction in that these twocircuit boards are preferably arranged directly adjacently to oneanother, for example in the same installation space as the controller,which installation space preferably lies open within a transmissionhousing of the hybrid transmission.

As already mentioned above, the electric machine is designed such thatthe rotor rotational axis extends parallel to the transmission inputshaft, i.e., in the transverse direction of the structure. According toa very advantageous development, the electric machine is arranged in thelongitudinal direction between the transmission input shaft and thepower electronics system, wherein, as already indicated above, accordingto an advantageous embodiment, it is arranged in the longitudinaldirection adjacently to at least one part of the power electronicssystem, wherein this part comprises at least the circuit board, while afurther part can be arranged extending in the longitudinal direction.The latter comprises, for example, a connection plug for the DC voltageconnection and an intermediate circuit capacitor, to name only a fewpreferred elements for the arrangement in this region.

An alternating current connection, which connects the electric machineand the power electronics system to one another, is arranged in thevertical direction below the rotor rotational axis according to a veryadvantageous development of the hybrid transmission according to theinvention. In the intended use, it can be arranged on the bottom of thecircuit board of the inverter on the one hand and the electric machineon the other hand so that the rest of the circuit board of the inverterextends upward in the vertical direction and thus next to the electricmachine in the longitudinal direction.

A direct current connection for the power electronics system is arrangedin the vertical direction above the rotor rotational axis and in thelongitudinal direction between the rotational axis of the differentialinput gear and the rotor rotational axis. In particular in the case of atransverse installation of the hybrid transmission in a vehicle, inwhich the direction defined here as the transverse direction correspondsto the transverse direction of the vehicle, the longitudinal directioncorresponds to the longitudinal direction of the vehicle, and thevertical direction corresponds to a vertical direction of the vehicle,this can be of decisive advantage since the direct current connection isthus moved back from the front region of the vehicle and therefore liesin a relatively well protected region in the event of a possibleaccident. The direct current connection is typically arranged on thetransmission housing of the transmission, which accommodates at leastthe power electronics system, the transmission control device, thehydraulic transmission controller, and the gear set. As a result, it isarranged in a relatively secure region in the event of a crash.

A particularly advantageous development of the hybrid transmissionaccording to the invention also provides that the transmission housinghas a cover arranged in the longitudinal direction on the side, facingaway from the transmission input shaft, of the transmission controldevice and of the power electronics system. The power electronics systemor at least the essential part with the circuit board of the inverterand the transmission control device for the electronic control of thegear set are therefore below the cover of the transmission housing,which otherwise also comprises the differential input gear, thetransmission input shaft, the at least one countershaft, the electricmachine, and the hydraulic transmission controller. By means of thisarrangement, the power electronics system and the transmission controldevice are relatively easily accessible. In the case of anaforementioned transverse installation of the hybrid transmission in avehicle, this cover then lies in the front in the direction of travel ofthe vehicle, i.e., in the longitudinal direction, so that the cover isaccessible from the front of the vehicle.

Further advantageous embodiments of the hybrid transmission according tothe invention also result from the exemplary embodiments which aredescribed in more detail below with reference to the figures.

BRIEF DESCRIPTION OF THE DRAWING FIGURES

In the drawings:

FIG. 1 is a schematic view of a possible embodiment of a hybridtransmission according to the invention from a viewing directiontransverse to the longitudinal direction;

FIG. 2 shows a drive train with a hybrid transmission according to theinvention in a schematic view perpendicular to the transverse direction;and

FIG. 3 shows an alternative embodiment of the hybrid transmissionaccording to the invention in an illustration analogous to that in FIG.1 .

DETAILED DESCRIPTION

FIG. 1 shows a hybrid transmission, denoted in its entirety by 1, for avehicle (not shown here). Three directions are shown schematically inthe illustration of FIG. 1 . A longitudinal direction x and a verticaldirection z span the drawing plane shown in FIG. 1 . A transversedirection y is perpendicular thereto, projecting into the drawing plane.In the illustration of FIG. 2 , the structure, together with furthercomponents, can be seen rotated further so that the longitudinaldirection x extends out of the plane of the sheet and the drawing planeis spanned by the transverse direction y and the vertical direction z.

The hybrid transmission 1 in the present case is partially situated in atransmission housing denoted by 2. The hybrid transmission 1 comprisesan electric machine 3 and a differential, of which a differential inputgear 4 is shown here. The latter is in engagement with a transmission,which comprises a transmission input shaft 5 and, in the exemplaryembodiment illustrated here, two countershafts 6. In front thereof inthe transverse direction shown in FIG. 2 is a clutch device denoted by 7and drawn in with a thicker line. This clutch device 7 is designed as adual clutch for the case shown in FIG. 1 , which can additionallycomprise a disconnect clutch. As will be explained later, a structurewith a disconnect clutch alone would also be conceivable.

The dual clutch transmission now illustrated here is connected to aninternal combustion engine 8 via the clutch device 7, as can be seen inthe illustration of FIG. 2 . In the context of the invention,“connected” generally means that the connection is indirect, via adevice (not shown here) for suppressing and damping rotationalvibrations, for example a dual mass flywheel or the like. The connectionof the clutch device 7 to the internal combustion engine 8 makes itpossible to drive the differential, and thus the vehicle via thedifferential input gear 4, on the one hand via the internal combustionengine 8 and on the other hand via the electric machine 3 with its rotorrotational axis 9. In this case, the electric machine 3 is arranged in aso-called side-by-side arrangement with a gear set of the hybridtransmission 1.

The side-by-side arrangement of the electric machine 3 is understood tomean that the rotor rotational axis 9 is arranged axially parallel andoffset to the transmission input shaft 5, and also axially parallel andoffset to the countershafts 6. The electric machine 3 can, for example,be coupled to a gearwheel or a toothing of the hybrid transmission 1 viaa spur gear pairing (not shown here) or also via a chain drive. Thistoothing can, for example, be an external toothing on a disk carrier ofthe clutch device or also a gearwheel in the gear set of thetransmission so that the electric machine 4 can output its power, forexample, to the transmission input shaft or in particular to one of thecountershafts 6.

In the longitudinal direction x, which is preferably also thelongitudinal direction of the vehicle so that the hybrid transmission isthus installed in the vehicle transversely to the vehicle longitudinaldirection or direction of travel, a hydraulic transmission controller 10is located adjacently to the transmission input shaft 5, and also to atransmission control device 11 which performs the task of electroniccontrol of the gear set of the hybrid transmission 1. In order tocontrol the electric machine 3, a power electronics system 12 isarranged in the vertical direction z above and adjacently to thetransmission control device 11 and comprises at least one circuit boardof an inverter, denoted by 13, which is connected to the electricmachine 3 via a three-phase alternating current connection 14. Inaddition, an intermediate circuit capacitor 15 is schematically drawn inthe power electronics system 12. Via a direct current connection 16,which is led out of the transmission housing 2 in a region denoted by17, the power electronics system 12 and thus ultimately the electricmachine 3 is connected to a traction battery (not shown here) of thevehicle equipped with the hybrid transmission 1.

In the longitudinal direction x, in the illustration of FIG. 1 on theright, the transmission housing 2 has a housing cover 18, which ispreferably arranged at the front in the direction of travel. This makesthe structure of the power electronics system 12 and of the transmissioncontrol device 11 easily accessible, while the direct current connection16, which is led out of the transmission housing 2 in the region denotedby 17, is moved to the rear in a corresponding manner in order toprovide the highest possible safety in the event of a crash of a vehicleequipped with the hybrid transmission 1.

Since this region 17 for implementing the direct current connection onthe housing 2 is located in the longitudinal direction x between therotor axis 9 of the electric machine 3 and a rotational axis 19 of thedifferential input gear 4, and thus is removed in the longitudinaldirection x both from the front of the transmission housing 2 with itscover 18 and from the opposite side, a high degree of safety is ensuredin the event of a crash.

The power electronics system 12 substantially comprises a primarysubregion with the circuit board 13 of the inverter, which is arrangedin the longitudinal direction x between the cover 18 and the electricmachine 3 so that the arrangement of the alternating current connectionbelow the rotor rotational axis 9 of the electric machine 3 ensures thatthe installation space next to the electric machine 3 is ideallyutilized. A further part, for example with the direct current connection16 and the intermediate circuit capacitor 15, of the power electronicssystem 12 can extend in the longitudinal direction x and is arrangedadjacently to the electric machine in the direction of the verticaldirection z so that the latter is thus partially enclosed by the powerelectronics system 12. In this case, the hydraulic transmissioncontroller 10 is arranged overlapping the electric machine 3 between thetransmission control device 11 and the gear set with its input shaft 5and the countershafts 6 so that it can interact directly with thecorresponding components within the transmission, which makes thestructure likewise compact and very efficient with regard to therequired cable lengths.

A circuit board 20 of the transmission control device 11 is arrangedadjacently in the vertical direction Z and parallel in the longitudinaldirection x to the circuit board 13 of the inverter. In the longitudinaldirection x, these should preferably have a distance from one another ofless than 20 mm. Ideally, they are arranged flush with one another alongthe vertical direction z.

In the illustration of FIG. 2 , with a view of the cover 18 of thetransmission housing 2, it can now be seen that the differential inputgear 4, the countershafts 6 (not shown here), and the transmission inputshaft 5 are arranged within the transmission housing, as are theelectric machine 3 and the hydraulic transmission controller 10, as wellas the combination of the transmission control device 11 at the bottomand the power electronics system 12, overlapping it, at the top. In thisscenario, a crankshaft of the internal combustion engine 8 indirectlydrives the clutch device 7, which can be designed here as a dual clutch.All in all, the structure can be realized extremely compactly, primarilyin the transverse direction y, i.e., along the main axes of thetransmission, e.g., the transmission input shaft 5. Accordingly, thestructure can be installed in the vehicle transversely to the directionof travel so that the schematic representation of FIG. 2 substantiallycorresponds to a viewing direction toward the front of a vehicleequipped with the drive train 21 shown there.

In this case, sufficient installation space remains in the transmissionhousing 2 to adapt the outer contour of this transmission housing 2 tofurther components and structures required in the vehicle. In theillustration of FIG. 1 , for example in the lower part of thetransmission housing 2 in the vertical direction z, an optional recessdenoted by 22 can thus be seen, in the region of which components of thesteering system of the vehicle could particularly preferably be arrangedoutside the transmission housing 2. The optional recess 22 isadvantageously arranged between the rotational axis 19 of thedifferential input gear 4 and the transmission control device 11 asviewed in the longitudinal direction x.

The transmission housing 2 is shown again in the illustration of FIG. 3. The optional recess 22 is not present here; the cover 18 of thetransmission housing 2 is not explicitly shown, in contrast to theillustration in FIG. 1 . Otherwise, the structure shown in FIG. 1 shouldlargely correspond to the structure shown in FIG. 3 . Here too, thedifferential input gear 4 can be seen, with its rotational axis 19, ascan the electric machine 3 with its rotor axis 9. A hydraulictransmission controller 10 is illustrated, and the transmission controldevice 11 is arranged adjacently thereto in the longitudinal directionx, wherein the explicit representation of the circuit board 20 has beenomitted. Thereabove is the power electronics system 12, wherein heretoo, the circuit board of the inverter, electrical connections, anddetails are omitted in the illustration.

The primary difference is now that the clutch device 7 is designed hereas a mere disconnect clutch. Unlike the structure in the illustration ofFIG. 1 , there is no control of a dual clutch transmission with twocountershafts 6; rather, there is a simple hybrid transmission with amodified gear set with an input shaft 5 and a single countershaft 6, viawhich the differential input gear 4 is driven accordingly. The structurecould be implemented, for example, in the form of a simple automatedmanual transmission which is suitably hybridized with the electricmachine 3. The latter is arranged in the side-by-side arrangementdescribed above in relation to the modified gear set in the hybridtransmission 1. The decisive structure of the integrated controller withthe power electronics system 12 and the transmission control device 11is identical to the exemplary embodiment described above.

Although the invention has been illustrated and described in detail byway of preferred embodiments, the invention is not limited by theexamples disclosed, and other variations can be derived from these bythe person skilled in the art without leaving the scope of theinvention. It is therefore clear that there is a plurality of possiblevariations. It is also clear that embodiments stated by way of exampleare only really examples that are not to be seen as limiting the scope,application possibilities or configuration of the invention in any way.In fact, the preceding description and the description of the figuresenable the person skilled in the art to implement the exemplaryembodiments in concrete manner, wherein, with the knowledge of thedisclosed inventive concept, the person skilled in the art is able toundertake various changes, for example, with regard to the functioningor arrangement of individual elements stated in an exemplary embodimentwithout leaving the scope of the invention, which is defined by theclaims and their legal equivalents, such as further explanations in thedescription.

What is claimed is:
 1. A hybrid transmission for a vehicle, the hybridtransmission comprising: a transmission input shaft extending in atransverse direction; at least one countershaft arranged parallel to thetransmission input shaft; a clutch device arranged coaxially with thetransmission input shaft and having at least one clutch; a differentialhaving a differential input gear, wherein a rotational axis of thedifferential input gear is arranged parallel to the transmission inputshaft; an electric machine having a rotor and a stator, wherein a rotorrotational axis is arranged parallel to the transmission input shaft;and a transmission control device, wherein, as viewed in a longitudinaldirection arranged perpendicular to the transverse direction, thedifferential input gear, the transmission input shaft, and atransmission controller comprising the transmission control device arearranged in succession in the recited sequence, wherein at least onepart of a power electronics system for the electric machine is arrangedadjacent to the transmission control device in a vertical direction,which is arranged perpendicular to the transverse direction andperpendicular to the longitudinal direction, and wherein the electricmachine is arranged adjacent to and above a hydraulic transmissioncontroller in the vertical direction and overlapping the hydraulictransmission controller in the longitudinal direction, and wherein thehybrid transmission further comprises a circuit board of an inverter ofthe power electronics system arranged adjacently in the verticaldirection and parallel in the longitudinal direction to a circuit boardof the transmission control device, wherein the circuit board of theinverter of the power electronics system is spaced less than 20 mm from,and arranged in the vertical direction flush with, the circuit board ofthe transmission control device.
 2. The hybrid transmission of claim 1,wherein the at least one part of the power electronics system arrangedadjacently to the transmission control device is arranged above thetransmission control device in operation.
 3. The hybrid transmission ofclaim 1, wherein a further part of the power electronics system extendsin the longitudinal direction and is arranged above the electric machinein the vertical direction.
 4. The hybrid transmission of claim 1,wherein the power electronics system is arranged at least partiallyoverlapping the transmission control device in the longitudinaldirection or in the transverse direction.
 5. The hybrid transmission ofclaim 1, wherein a rotor rotational axis of the electric machine isarranged in the longitudinal direction between the transmission inputshaft and the at least one part of the power electronics system.
 6. Thehybrid transmission of claim 1, wherein the electric machine is arrangedin the longitudinal direction adjacent to the at least one part of thepower electronics system.
 7. The hybrid transmission of claim 5, furthercomprising: an alternating current connection, connecting the electricmachine and the power electronics system, arranged in the verticaldirection below the rotor rotational axis.
 8. The hybrid transmission ofclaim 1, further comprising: a direct current connection for the powerelectronics system arranged in the vertical direction above the rotorrotational axis and in the longitudinal direction between the rotationalaxis of the differential input gear and the rotor rotational axis. 9.The hybrid transmission of claim 1, further comprising: a transmissionhousing accommodating at least the differential input gear, thetransmission input shaft, the at least one countershaft, the electricmachine, the transmission control device, the hydraulic transmissioncontroller and the power electronics system, wherein the transmissionhousing comprises a housing cover arranged in the longitudinal directionon a side, facing away from the transmission input shaft, of thetransmission control device and of the at least one part of the powerelectronics system.
 10. The hybrid transmission of claim 1, wherein thetransverse direction, the longitudinal direction, and the verticaldirection, in a case of a hybrid transmission installed in a vehicle,correspond in the specified sequence to the vehicle transversedirection, the vehicle longitudinal direction, and the vehicle verticaldirection.
 11. The hybrid transmission of claim 1, wherein the clutchdevice has a dual clutch or a disconnect clutch.